DNA polymerase switching: I. Replication factor C displaces DNA polymerase alpha prior to PCNA loading

J Mol Biol. 2000 Jan 28;295(4):791-801. doi: 10.1006/jmbi.1999.3394.


An important not yet fully understood event in DNA replication is the DNA polymerase (pol) switch from pol alpha to pol delta. Indirect evidence suggested that the clamp loader replication factor C (RF-C) plays an important role, since a replication competent protein complex containing pol alpha, pol delta and RF-C could perform pol switching in the presence of proliferating cell nuclear antigen (PCNA). By using purified pol alpha/primase, pol delta, RF-C, PCNA and RP-A we show that: (i) RF-C can inhibit pol alpha in the presence of ATP prior to PCNA loading, (ii) RF-C decreases the affinity of pol alpha for the 3'OH primer ends, (iii) the inhibition of pol alpha by RF-C is released upon PCNA loading, (iv) ATP hydrolysis is required for PCNA loading and subsequent release of inhibition of pol alpha, (v) under these conditions a switching from pol alpha/primase to pol delta is evident. Thus, RF-C appears to be critical for the pol alpha to pol delta switching. Based on these results, a model is proposed in which RF-C induces the pol switching by sequestering the 3'-OH end from pol alpha and subsequently recruiting PCNA to DNA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Animals
  • Cattle
  • Cytosol / enzymology
  • DNA Polymerase I / metabolism*
  • DNA Polymerase III / metabolism*
  • DNA Primase / metabolism
  • DNA Replication*
  • DNA-Binding Proteins / metabolism*
  • HeLa Cells
  • Homeodomain Proteins*
  • Humans
  • Kinetics
  • Minor Histocompatibility Antigens
  • Proliferating Cell Nuclear Antigen / metabolism*
  • Proto-Oncogene Proteins c-bcl-2*
  • Replication Protein C
  • Repressor Proteins*
  • Saccharomyces cerevisiae Proteins*
  • Simian virus 40 / genetics
  • Simian virus 40 / physiology
  • Substrate Specificity
  • Thymus Gland / enzymology
  • Virus Replication


  • BCL2-related protein A1
  • DNA-Binding Proteins
  • Homeodomain Proteins
  • MATA1 protein, S cerevisiae
  • Minor Histocompatibility Antigens
  • Proliferating Cell Nuclear Antigen
  • Proto-Oncogene Proteins c-bcl-2
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Adenosine Triphosphate
  • DNA Primase
  • DNA Polymerase I
  • DNA Polymerase III
  • Replication Protein C